SSD1858 Solomon Systech, SSD1858 Datasheet - Page 36

• Manufacturer Part Number: SSD1858
• Description: LCD Segment / Common Driver
• Manufacturer: Solomon Systech

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SSD1858
8.30 OTP setting and programming
OTP (One Time Programming) is a method to adjust Vout. In order to eliminate the variations of
LCD module in term of contrast level, OTP can be used to achieve the best contrast of every
LCD modules.
OTP setting and programming should include two major steps of (1) Find the OTP offset and
(2) OTP programming as following,
Example 1:
Contrast value of original initialization = 0x20
Contrast value of the best visual contrast = 0x24
OTP setting steps = 0x24 - 0x20 = +4
OTP setting commands should be (0x82, 0x14)
Example 2:
Contrast value of original initialization = 0x20
Contrast value of the best visual contrast = 0x1B
OTP setting steps = 0x1B - 0x20 = -5
OTP setting commands should be (0x82, 0x1B)
Verify the result by repeating step 1. (2) – (3)
Step 1. Find OTP offset
(1) Hardware Reset (sending an active low reset pulse to
(2) Send original initialization routines
(3) Set and display any test patterns
(4) Adjust the contrast value (0x81, 0x00~0x3F) until there is the best visual contrast
(5) OTP setting steps = Contrast value of the best visual contrast - Contrast value of original
Step 2. OTP programming
(6) Hardware Reset (sending an active low reset pulse to
(7) Enable Oscillator (0xAB)
(8) Connect an external Vout (see diagram below)
(9) Send OTP setting commands that we find in step 1 (0x82, 0x10~0x1F)
(10) Send OTP programming command (0x83)
(11) Wait at least 2 seconds
(12) Hardware Reset
initialization
SSD1858
Rev 1.1
09/2002
RES#
Vout
Figure 11 - OTP programming circuitry
GND
+
-
C
(1) & (6) & (12)
(8)
Note: R = 1K ~ 10k ohm
R
RES# pin)
RES# pin)
C = 1u ~ 4.7u F
GND
16.5-17.5V
SOLOMON